Levelling
Levelling, Important Terminologies In Levelling, Elevation & Altitude, Reduced Level, Mean Sea Level, Bench Marks(B.M)– G.T.S Bench Marks, Permanent Bench Marks, Temporary Bench Marks, Arbitrary Bench Marks. Measurement in Leveling Work- Horizontal Line, Vertical Line, Level Line, Back Sight Reading, Fore Sight Reading, Intermediate Sight Reading. Method to Find Reduced Level- Height of Instrument, Rise and Fall Method. Inverted Staff, Correction Required in Levelling Work- Correction due to Earth Curvature (Cc), Correction due to Refraction (CR), Combined Correction due to Both (C). Distance of Visible Horizon- When height of any one point is considered, When height of both points are considered. Reciprocal Leveling – When the instrument near A, When the instrument near B, Collimation error– When Area is Large, When Area is small, Angular / Inclination Error, Sensitivity of Bubble Tube , The sensitivity of level tube increases with?.
Topics
In liner measurements,we details discuss about procedure in chain surveying,basic definition of chain surveying- main station, tie station, main survey line, tie line/ subsidiary line, base line, check line/ proof line, offset, chainage, well conditioned triangle.Correction in chaining,limiting length of offsets.
In special instrument, we detailed discuss about hand leveling, abney level, indian pattern clinometer, ceylon ghat tracer, sextant, site square, mining dial, brunton’s compass, pantagraph, eidograph.